Recalling logical volumes to cache from physical media volumes for redundant storage in automated data storage libraries

1. A method for recalling logical volumes of data stored by an automated data storage library, said recall in response to a recall request; said library storing logical volumes, including logical volumes to be copied for redundant storage; said library having a plurality of storage shelves for storing physical media volumes, said physical media volumes each capable of storing a stacked plurality of said logical volumes; said library having at least one data storage drive for reading and/or writing said stacked logical volumes of said physical media volumes; said library having at least one accessor for transporting said physical media volumes amongst said storage shelves and said at least one data storage drive and mounting and demounting said physical media volumes at said at least one data storage drive; and said library having a cache storage for initially storing said logical volumes and storing said recalled logical volumes, said library migrating said logical volumes from said cache storage to said physical media volumes as stacked logical volumes; said recall request comprising a request for recalling one said logical volume to be copied; said method comprising the steps of: responding to said recall request of said logical volume to be copied, which logical volume has been migrated to said physical media volumes, determining which said physical media volume contains said requested migrated logical volume; identifying all said logical volumes to be copied, in addition to said requested migrated logical volume, that are migrated and stored as stacked logical volumes on said determined physical media volume containing said requested migrated logical volume; selecting up to a predetermined number N of said identified logical volumes including said requested migrated logical volume; employing said at least one accessor to transport and mount said determined physical media volume to said at least one data storage drive; recalling said selected logical volumes of said mounted physical media volume, via said at least one data storage drive, to said cache storage in accordance with said selection; and providing, in response to said recall request, a recall list of said recalled selected logical volumes.

2. The method of claim 1 , wherein said selecting-step additionally comprises giving priority to said identified logical volumes most closely adjacent to said requested migrated logical volume.

3. The method of claim 1 , wherein said automated data storage library is coupled to a plurality of directors, one of said directors supplying said recall request, and wherein said step of providing a recall list comprises providing said recall list of said recalled selected logical volumes to all of said plurality of directors.

4. The method of claim 3 , additionally comprising the step of, all said plurality of directors responding to said provided recall list, copying said recalled logical volumes-in parallel to said second automated data storage library.

5. The method of claim 1 , wherein said library maintains a record of all logical volumes stored in said library, and said record identifying said physical media volume containing said logical volume, each record of said logical volumes to be copied having a flag identifying said logical volume as requiring copying, and wherein said identifying step additionally comprises identifying said logical volumes of said record both identified as contained in said physical media volume and as having said flag.

6. The method of claim 1 , wherein said selecting step additionally comprises arranging a selection list of said selected logical volumes in a sequence in accordance with the order that said selected logical volumes are written on said determined physical media volume.

7. An automated data storage library for storing logical volumes, including logical volumes to be copied for redundant storage, said library coupled to a source of recall requests for recalling said logical volumes, said recall request comprising a request for recalling one said logical volume to be copied, said library comprising: a plurality of storage shelves for storing physical media volumes, said physical media volumes each-capable of storing a stacked plurality of said logical volumes; at least one data storage drive for reading and/or writing said stacked logical volumes of said physical media volumes; at least one accessor for transporting said physical media volumes amongst said storage shelves and said at least one data storage drive and mounting and demounting said physical media volumes at said at least one data storage drive; a cache storage for storing said logical volumes; and a library controller, said library controller performing the steps of: migrating said logical volumes from said cache storage to said physical media volumes as stacked logical volumes; responding to said recall request of said logical volume to be copied, which logical volume has been migrated to said physical media volumes, determining which said physical media volume contains said requested migrated logical volume; identifying all said logical volumes to be copied, in addition to said requested migrated logical volume, that are migrated and stored as stacked logical volumes on said determined physical media volume containing said requested migrated logical volume; selecting up to a predetermined number N of said identified logical volumes including said requested migrated logical volume; employing said at least one accessor to transport and mount said determined physical media volume to said at least one data storage drive; recalling said selected logical volumes of said mounted physical media volume, via said at least one data storage drive, to said cache storage in accordance with said selection; and providing, in response to said recall request, a recall list of said recalled selected logical volumes.

8. The automated data storage library of claim 7 , wherein said library controller additionally gives priority to said identified logical volumes most closely adjacent to said requested migrated logical volume in selecting said up to N identified logical volumes.

9. The automated data storage library of claim 7 , wherein said coupled source of recall requests comprises a plurality of directors, one of said directors supplying said recall request, and wherein said library controller provides said recall list of said recalled selected logical volumes to all of said plurality of directors.

10. The automated data storage library of claim 7 , wherein said library controller additionally maintains a record of all logical volumes stored in said library, said record identifying said physical media volume containing said logical volume, each record of said logical volumes to be copied having a flag identifying said logical volume as requiring copying; and said library controller identifies said logical volumes to be copied by identifying those of said logical volumes of said record, both as contained in said physical media volume and as having said flag.

11. The automated data storage library of claim 7 , wherein said library controller, in selecting said up to N identified logical volumes, additionally arranges a selection list of said selected logical volumes in a sequence in accordance with the order that said selected logical volumes are written on said determined physical media volume.

12. The automated data storage library of claim 7 , wherein said library controller provides said recall list as an unsolicited ATTENTION message.

13. A data storage library system for redundantly storing and accessing logical volumes of data, said library system comprising: at least one director, said director providing recall requests, said recall request comprising a request for recalling one said logical volume to be copied for redundant storage; and at least two automated data storage libraries for redundantly storing said logical volumes, each said library coupled to said at least one director, each said library comprising: a plurality of storage shelves for storing physical media volumes, said physical media volumes each capable of storing a stacked plurality of said logical volumes; at least one data storage drive for reading and/or writing said stacked logical volumes of said physical media volumes; at least one accessor for transporting said physical media volumes amongst said storage shelves and said at least one data storage drive and mounting and demounting said physical media volumes at said at least one data storage drive; a cache storage for storing said logical volumes; and a library controller, said library controller: migrating said logical volumes from said cache storage to said physical media volumes as stacked logical volumes; responding to said director recall request of said logical volume to be copied, which logical volume has been migrated to said physical media volumes, determining which said physical media volume contains said requested migrated logical volume; identifying all said logical volumes to be copied, in addition to said requested migrated logical volume, that are migrated and stored as stacked logical volumes on said determined physical media volume containing said requested migrated logical volume; selecting up to a predetermined number N of said identified logical volumes including said requested migrated logical volume; employing said at least one accessor to transport and mount said determined physical media volume to said at least one data storage drive; recalling said selected logical volumes of said mounted physical media volume, via said at least one data storage drive, to said cache storage in accordance with said selection; and providing to said director, in response to said recall request, a recall list of said recalled selected logical volumes.

14. The data storage library system of claim 13 , wherein said library controller of said automated data storage library additionally gives priority to said identified logical volumes most closely adjacent to said requested migrated logical volume in selecting said up to N identified logical volumes.

15. The data storage library system of claim 13 , comprising a plurality of directors, one of said directors supplying said recall request, and wherein said library controller of said automated data storage library provides said recall list of said recalled selected logical volumes to all of said plurality of directors.

16. The data storage library system of claim 15 , wherein all of said plurality of directors respond to said provided recall list, copying said recalled logical volumes in parallel to the other of said at least two automated data storage libraries.

17. The data storage library system of claim 13 , wherein said library controller of said automated data storage library additionally maintains a record of all logical volumes stored in said library, said record identifying said physical media volume containing said logical volume, each record of said logical volumes to be copied having a flag identifying said logical volume as requiring copying; and said library controller identifies said logical volumes to be copied by identifying those of said logical volumes of said record, both as contained in said physical media volume and as having said flag.

18. The data storage library of claim 13 , wherein said library controller of said automated data storage library, in selecting said up to N identified logical volumes, additionally arranges a selection list of said selected logical volumes in a sequence in accordance with the order that said selected logical volumes are written on said determined physical media volume.

19. A computer program product usable with at least one programmable computer processor, for recalling logical volumes of data stored by an automated data storage library, said recall in response to a recall request; said library storing logical volumes, including logical volumes to be copied for redundant storage; said library having a plurality of storage shelves for storing physical media volumes, said physical media volumes each capable of storing a stacked plurality of said logical volumes; said library having at least one data storage drive for reading and/or writing said stacked logical volumes of said physical media volumes; said library having at least one accessor for transporting said physical media volumes amongst said storage shelves and said at least one data storage drive and mounting and demounting said physical media volumes at said at least one data storage drive; and said library having a cache storage for initially storing said logical volumes and storing said recalled logical volumes, said library migrating said logical volumes from said cache storage to said physical media volumes as stacked logical volumes; said recall request comprising a request for recalling one said logical volume to be copied; comprising: computer readable program code which causes said at least one computer processor comprising a library controller of said automated data storage library to respond to said recall request of said logical volume to be copied, which logical volume has been migrated to said physical media volumes, determining which said physical media volume contains said requested migrated logical volume; computer readable program code which causes said at least one computer processor to identify all said logical volumes to be copied, in addition to said requested migrated logical volume, that are migrated and stored as stacked logical volumes on said determined physical media volume containing said requested migrated logical volume; computer readable program code which causes said at least one computer processor to select up to a predetermined number N of said identified logical volumes including said requested migrated logical volume; computer readable program code which causes said at least one computer processor to employ said at least one accessor to transport and mount said determined physical media volume to said at least one data storage drive; computer readable program code which causes said at least one computer processor to recall said selected logical volumes of said mounted physical media volume, via said at least one data storage drive, to said cache storage in accordance with said selection; and computer readable program code which causes said at least one computer processor to provide, in response to said recall request, a recall list of said recalled selected logical volumes.

20. The computer program product of claim 19 , wherein said computer readable program code additionally causes said at least one computer processor to give priority to said identified logical volumes most closely adjacent to said requested migrated logical volume in selecting said up to N identified logical volumes.

21. The computer program product of claim 19 , wherein said coupled source of recall requests comprises a plurality of directors, one of said directors supplying said recall request, and wherein said computer readable program code additionally causes said at least one computer processor to provide said recall list of said recalled selected logical volumes to all of said plurality of directors.

22. The computer program product of claim 19 , wherein said computer readable program code additionally causes said at least one computer processor to maintain a record of all logical volumes stored in said library, said record identifying said physical media volume containing said logical volume, each record of said logical volumes to be copied having a flag identifying said logical volume as requiring copying; and said computer readable program code additionally causes said at least one computer processor to identify said logical volumes to be copied by identifying those of said logical volumes of said record, both as contained in said physical media volume and as having said flag.

23. The computer program product of claim 19 , wherein said computer readable program code which causes said at least one computer processor to select up to N said identified logical volumes, additionally causes said processor to arrange a selection list of said selected logical volumes in a sequence in accordance with the order that said selected logical volumes are written on said determined physical media volume.

24. The computer program product of claim 19 , wherein said computer readable program code which causes said at least one computer processor to provide said recall list, causes said processor to provide said recall list as an unsolicited ATTENTION message.